Ground engaging surface for endless tracks and wheels

ABSTRACT

A ground engaging segment providing a running surface for wheels, endless tracks and the like, which is not pneumatic in nature, thereby not susceptible to puncture, and which is resiliently flexible to offer some resistance to shock. The ground engaging segment comprises a base and a number of removable, hollow, tubular ground engaging elements which extend transversely of the direction of travel of the running surface. Said ground engaging elements include an inner face for engagement to the base and an outer face for contact with the ground surface, and angular shaped side faces between the inner and outer faces allowing for resilient flexibility under normal load conditions. It is preferable that the ground engaging elements are open at their ends to allow for dissipation of heat and are arranged in circumferential rows, defining a chevron pattern, to prevent resultant side thrust imposed upon the running surface. In addition, the ground engaging elements are constructed angularly to provide a line about which the side faces can flex, and include a flexible internal reinforcement, built in to the walls of the faces of the ground engaging element to provide reinforcement for the ground engaging element, while maintaining flexibility.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a continuation of U.S. patent application Ser. No.07/792,887 of Burns filed Nov. 15, 1991 and entitled "GROUND-ENGAGINGSURFACE FOR ENDLESS TRACKS AND WHEELS", now abandoned, which, in turn,is a continuation of U.S. patent application Ser. No. 07/391,505 ofBurns filed as PCT/AU88/00023, Jan. 29, 1988, and entitled"GROUND-ENGAGING SURFACE FOR ENDLESS TRACKS AND WHEELS" now U.S. Pat.No. 5,154,490 issued Oct. 13, 1992.

This invention relates to means providing a running surface for wheels,endless tracks and the like.

The present invention seeks to provide a running surface for wheels,endless tracks and the like which can resiliently flex so as to offersome resistance to shock and which is not pneumatic in nature andthereby not susceptible to puncturing as is the case with pneumatictires.

In one form the invention resides in means providing a running surfacecomprising a base and a plurality of elongated, hollow ground engagingelements carried on the base, the ground engaging elements extendingtransversely of the direction of travel of the running surface and beingof a construction so as to resiliently deform under load.

While the ground engaging elements may extend in a direction orthogonalto the direction of travel of the running surface, it is preferable thatthey are inclined to such direction. Furthermore, while each groundengaging element may extent the full width of the running surface, it ispreferable that the elements are arranged in a fashion which does notimpose a resultant side thrust on the running surface (such ascircumferential rows arranged to define a chevron pattern). With achevron pattern, there is in use no resultant side thrust imposed uponthe running surface as would be the case with tubular elements extendingin an inclined fashion across the full width of the running surface.

In circumstances where a running surface according to the invention isfor use with a wheel, the base may simply be the rim of the wheel or aband adapted to be fitted onto the rim. In circumstances where a runningsurface according to the invention is for use with an endless track, thebase may comprise a flexible endless band passing around end rollersthereby to constitute the endless track.

The ground engaging elements may be formed integral with the base, butfor preference are formed separately of the base and fixed thereto.Preferably, the ground engaging elements are detachably fixed to thebase by removable fixing means.

The ground engaging elements may be in the form of tubular elementswhich are preferably open at their ends. By being open at their ends,the tubular elements are ventilated to facilitate dissipation of heat.

In one arrangement, the tubular elements may be of a cross-section whichpresents an outwardly facing convex surface. With this arrangement, itis convenient for the tubular element to be partly circular incross-section, having an arcuate portion and a generally flat webportion. The arcuate portion defines said convex surface and the webportion facilitates fixing of the element to said base. The generallyflat web portion may be profiled to conform with curvature of the base.Alternatively, the tubular elements may be circular in cross-section.

In another arrangement, the tubular elements may be of a cross-sectionwhich provides an inner longitudinal face for engagement against thebase, an outer longitudinal face for contacting the ground andlongitudinal side faces between the inner and outer faces, the sidefaces being constructed to be resiliently flexible under normal loadconditions. Each side face may be of angular or other construction so asto provide a line about which it can flex. The outer face may beprovided with a tread formation.

The tubular elements may be formed from rubber or other elastomericmaterial. The rubber or other elastomeric material may be provided withreinforcement.

In still another arrangement, the elongated hollow tubular elements maybe in the form of loops which are preferably formed from a length ofresilient material arranged in sinuous formation having alternatingcrests and troughs, the length of material being secured to the base atlocations corresponding to at least some of the troughs.

There may be provided at least one further row of said loops, the loopsof each row being staggered with respect to the loops in a neighboringrow. In this way, the ground engaging surface can travel over the groundin a more uniform manner.

Where the tubular elements constitute a tire, the length of resilientmaterial may be anchored to the peripheral surface of a wheel on whichthe tire is to be mounted or onto a band which can be located onto therim of such a wheel. Where the ground engaging surface is associatedwith an endless track, the length of material is secured to an innerband of flexible material so as to constitute an endless track which inuse is fitted around spaced rollers forming part of the endless trackdrive system.

The hollow ground engaging elements may be defined by a plurality ofsegments located one adjacent another around the running surface witheach segment being detachably fixed to said base.

Each segment may carry one or more tubular elements.

In one embodiment, each segment has a pair of oppositely extendingmounting flanges each adapted to co-operate with the neighboring flangeon the next adjacent segment in such a manner that the co-operatingflanges are positioned one upon the other to receive common anchoringmeans. The common anchoring means may comprise one or more bolts eachextending through aligned mounting holes in the co-operating flanges andthe base.

In a further embodiment, each segment carries one tubular element andincludes an opening extending along the tubular element, a mountingflange provided on each longitudinal side of the opening, each mountingflange being constructed of a plurality of spaced flange sections, theflange sections and spacings therebetween of one mounting flange beingcomplementary to the flange sections and spacings therebetween of theother mounting flange, each flange section including an outwardlyextending portion extending away from said opening and an inwardlyextending portion extending into said opening, whereby the flangesections of co-operating mounting flanges inter-engage in a manner suchthat the flange sections of each mounting flange located in the spacingsbetween flange sections of the other mounting flange. Preferably saidsegment is detachably fixed to said base by anchoring means disposed insaid tubular element and engaging said inwardly extending flangesections of said segment and further engaging outwardly extending flangesections of co-operating flanges of respective neighboring segments.

In another form the invention resides in a ground engaging member for awheel or endless track comprising a tubular element of resilientlyflexible construction having a cross-section presenting an outwardlyfacing convex surface.

The tubular element of the ground engaging member may comprise anarcuate portion defining said convex surface and a generally flat webportion extending across said convex portion.

In still another form the invention resides in a ground engaging memberfor a wheel or endless track comprising a tubular element having aninner longitudinal face for engagement against part of the wheel orendless track, an outer longitudinal face for contacting the ground andlongitudinal side faces between the inner and outer faces, the sidefaces being constructed to be resiliently flexible.

In still another form the invention resides in a segment carrying atleast one elongated ground engaging element, the segment comprises abody including said at least one elongated ground engaging element, thebody having a mounting face a pair of mounting flanges provide onopposed sides of the body and extending longitudinally with respect tosaid at least one ground engaging element, one flange having a faceco-planar with said mounting face and the other flange having acorresponding face spaced from said mounting face by an amountcorresponding to the thickness of said one flange.

Preferably the interior of said at least one elongated ground engagingelement opens onto said mounting face.

Preferably the interior of said at least one elongated ground engagingelement opens onto said mounting face for the entire length of theground engaging element.

In still another form the invention resides in a segment carrying aground engaging element for a wheel or endless track, said segmentincluding an opening extending along the tubular element, a mountingflange provided on each longitudinal side of the opening, each mountingflange being constructed of a plurality of spaced flang sections, theflange sections and spacings therebetween of one mounting flange beingcomplementary to the flange sections and spacings therebetween of theother mounting flange, each flange section including an outwardlyextending portion extending away from said opening and an inwardlyextending portion extending into said opening.

The invention will be better understood by reference to the followingdescription of several specific embodiments thereof as shown in theaccompanying drawings which:

FIG. 1 is an isometric view of a wheel fitted with means providing arunning surface according to the first embodiment;

FIG. 2 is an end view of the running surface of FIG. 1;

FIG. 3 is a view of apart of the running surface of the firstembodiment, showing the profile of the tubular elements;

FIG. 4 is a view similar to FIG. 3, showing the profile of another formof tubular element;

FIG. 5 is also a view similar to FIG. 3, showing the profile of stillanother form of tubular element;

FIG. 6 is a fragmentary view showing a pattern in which tubular elementsmay be arranged as an alternative to the pattern in the first embodimentas illustrated in FIG. 2;

FIG. 7 is a fragmentary view illustrating a further pattern in which thetubular element may be arranged;

FIG. 8 is a fragmentary view illustrating a still further pattern inwhich the tubular elements may be arranged;

FIG. 9 is an end view of a further form of tubular element;

FIG. 10 is a plan view of the tubular element shown in FIG. 9;

FIG. 11 is a cross-section on line 11--11 of FIG. 10;

FIG. 11a is a view similar to FIG. 11 showing a tubular ground-engagingelement, or tire element, as shown in FIGS. 9-11, with the addition of atread formation, mounted on a wheel rim adjacently to portions of twofurther such elements, the latter being shown in phantom lines;

FIG. 11b is another view similar to the sectional view of FIG. 11 of thetubular, ground-engaging element of FIGS. 9-11, shown inverted in aground-contacting position deforming in response to a load;

FIG. 12 is a schematic perspective view of a wheel fitted with meansproviding running surface constructed according to a further embodiment;

FIG. 13 is a fragmentary view showing part of the running surface of thewheel of FIG. 12 in more detail;

FIG. 14 is an end view of a segment which forms part of the runningsurface shown in FIG. 12;

FIG. 15 is a perspective view of the segment shown in FIG. 14;

FIG. 16 is a schematic side view of the wheel shown in FIG. 12 with therunning surface deformed on encountering an obstacle;

FIG. 17 is a fragmentary view of part of a running surface of a wheel,the running surface being constructed according to a still furtherembodiment;

FIG. 18 is a section on line 18--18 of FIG. 17, with segment anchoringmeans removed to reveal the mounting flanges;

FIG. 19 is an perspective view of a segment from which running surfaceaccording to the embodiment of FIG. 17 is constructed;

FIG. 20 is a section on line 20--20 of FIG. 19;

FIG. 21 is a perspective view of a running surface according to a stillfurther embodiment mounted on a wheel so as to provide a tire for thewheel;

FIG. 22 is a side view of FIG. 21;

FIG. 23 is an end view of the arrangement of FIG. 21;

FIG. 24 is a section along the line 24--24 of FIG. 22;

FIG. 25 is a part-sectional elevational of one form of endless trackaccording to a further embodiment; and

FIG. 26 is a part-sectional elevation of a second form of a trackaccording to the embodiment of FIG. 25.

The embodiment shown in FIGS. 1, 2 and 3 of the drawings is directed toa means 10 providing a running surface 11 for a wheel of a mobileapparatus or work vehicle such as an earth moving machine oragricultural machine. The embodiments of FIGS. 4-26 show modificationsof the means 10, and their use in providing a running surface 11, suchas a segmental tire, or track, for a mobile apparatus, such as avehicle.

The running surface 11 comprises a plurality of spaced tubular elements12 mounted on the outer periphery of an endless base 15 which in use isfitted onto the rim 16 of the vehicle wheel. The tubular elements 12extend transversely of the direction of travel of the running surface,as best seen in FIGS. 1 and 2 of the drawings.

The tubular elements are of a construction so as to deform resilientlyunder normal load conditions. In this embodiment, the tubular elementsare each of circular cross-section and formed from a length of heavyduty mining hose. Each tubular element is fixed to the base 15 by meansof a reinforcing strip 17 which is positioned within the tubular elementand secured to the base 15 and the rim 16 by fixing elements 18 in theform nut and bolt assemblies, as best seen in FIG. 3 of the drawings.

Referring now to FIG. 4 of the drawings, the running surface accordingto the second embodiment is similar to that of the first embodiment withthe exception that the tubular elements 12 are substantially triangularin cross-section rather than circular.

Referring now to FIG. 5 of the drawings, the running surface accordingto the third embodiment is also similar to that of the first embodimentwith the exception that the tubular elements 12 are part circular incross-section, having an arcuate portion 13 and a web portion 14 atwhich the tubular element is fixed to the base 15.

In the running surfaces according to the embodiments describedpreviously, the tubular elements 12 extends transversely of thedirection of travel of the running surface for the full width of therunning surface, as best shown in FIG. 2 of the drawings. Thisarrangement has a deficiency in travel in that a side thrust is imposedupon the portion of the running surface in contact with the ground owingto the particular arrangement of the tubular elements.

FIG. 6 of the drawings shows an alternative arrangement of tubularelement in which elements are arranged in a chevron pattern. Thisarrangement has the benefit that in travel there is no resultant sidethrust imposed upon the portion of the running surface in contact withthe ground. A separate tubular element may provide each arm of thechevron or each tubular element may be so configured as to provide twoarms of the chevron.

FIGS. 7 and 8 of the drawings illustrates still further alternativearrangements for the tubular elements.

Because the tubular elements 12 are constructed to resiliently deformunder normal load conditions, the running surface has the ability to atleast partly cushion bumps and surface irregularities encountered as ittravels over the ground. The resilient nature of the tubular elementspermits the running surface to operate on finished road surfaces, whilealso providing traction in circumstances where unstable ground, such asloose soil, is encountered.

The tubular element shown in FIGS. 9, 10 and 11 comprises an innerlongitudinal face 20 for detachable engagement against the base, anouter longitudinal face 21 for contacting the ground and longitudinalside faces 22 between the inner and outer faces.

The side faces 22 are constructed to deform resiliently under normalload conditions. In particular, each side face 22 is of angularconstruction to provide a line at 23 extending along the length of theface about which the face can flex.

The outer face 21 is provided with a tread formation (not shown).

The tubular element is provided with internal reinforcement means 24 (asshown in FIG. 11) which reinforces the element while allowing resilientdeformation in the manner described.

The tubular element is configured into a V-formation (as best seen inFIG. 10) so as to provide a chevron pattern on the wheel.

The embodiment shown in FIGS. 12 to 16 of the drawings is directed tomeans providing a running surface for a wheel having a rim 27. Therunning surface is provided by a plurality of tubular elements 30adapted to be detachably mounted onto the rim 27. The tubular elements30 extend transversely of the direction of travel of the running surfaceand are configured in a V-formation chevron pattern so as to provide achevron pattern on the wheel.

The tubular elements 30 are formed of resiliently flexible material soas to deform resiliently under load thereby to provide cushioning. Theyare of generally circular cross-section, with an opening 34 extendinglongitudinally along the bottom thereof. The ends of the tubularelements are also open.

The tubular elements 30 are defined by segments 35 releasably mounted onthe wheel rim 27 one adjacent another circumferentially around therunning surface, with the inner face 36 of each segment located againstthe rim. In this embodiment, each segment 35 defines one tubular element30 although it may be constructed to define a plurality of elements.Each segment is provided with a pair of oppositely projecting flanges37, 38 each adapted to co-operate with the neighboring flange on thenext adjacent segment in such a manner that the co-operating flanges arepositioned one upon the other to receive a common anchoring means (notshown). More particularly, the flanges 37, 38 extend longitudinally withrespect to the tubular element. The flange 37 is so positioned as toprovide a mounting face 39 which is co-planar with the inner face 36 ofthe segment 35 and which is adapted to locate against the rim 27. Flange38 provides a mounting face 41 which is outwardly spaced from the innerface 36 of the segment by an amount corresponding to the thickness offlange 37. Thus, space 43 defined between mounting face 41 of flange 38and the plane of the inner face 36 of the segment 35 provides alongitudinal cavity for receiving flange 37 of the immediately adjacentsegment. In this way, flange 38 of any one segment and the flange 37 ofthe immediately adjacent segment co-operate in the manner describedpreviously.

The flanges 37 and 38 are each provided with longitudinally spacedmounting holes 45. Corresponding mounting holes 45 of co-operatingflanges are arranged to align with one another to receive said commonanchoring means in the form of bolts which anchor the co-operatingflanges to the rim 27. With this mounting arrangement, the segments canbe easily replaced on an individual basis in the event of damage.

FIG. 16 illustrates several tubular elements 30 in a deformed state as aresult of encountering an obstacle in the path of the wheel.

The embodiment shown in FIGS. 17 to 20 is directed to a running surfacewhich is somewhat similar to that of the last preceding embodiment withthe exception of differences in the construction of the segment 35.

In this embodiment, the segments 35 each comprise a tubular element 51having an opening 53 extending longitudinally along the tubular element.On both longitudinal sides of the opening 53 there are mounting flanges55, 57. The mounting flanges 55, 57, which are separated by space 58co-operate to define a mounting face 59 for engagement against the outerperiphery of the wheel rim 27.

The mounting flange 55 is defined by a plurality of flange sections 61spaced regularly along the line of the flange. The spacing betweensuccessive flange sections 61 are identified by reference numeral 71.Similarly, the mounting flange 57 is defined by a plurality of flangesections 63 spaced regularly along the length of the flange and incomplementary relationship to flange sections 61 of flange 55. Thespacings between successive flange sections 63 are identified byreference numeral 72.

Each mounting flange section 61 has outwardly extending portion 65 whichextends away from the opening 53 in the tubular element and an inwardlyextending portion 67 which extends into the opening. Similarly, eachmounted flange section 63 has an outwardly extending portion 66 whichextends away from the opening 53 and an inwardly extending portion 68which extends into the opening.

When the segments are mounted one adjacent another around the peripheryof the wheel rim, flange 55 of each segment inter-engages withcomplementary flange 57 of the neighboring segment. More particularly,flange sections of each flange locate in the spacings between the flangesections of the other flange, with the outwardly directed flangeportions each flange locating adjacent, and co-operating with, theinwardly directed flange portions of the complementary flange. Thus, oneach side of the space 58 there is a set of co-operating flangeportions, one set being co-operating flange portions 66 and 67 and theother set being co-operating flange portions 65 and 68, as best seen inFIG. 18.

The co-operating flange portions are detachably fixed to the wheel rimby an anchoring means 73 in the form of an anchoring strap 74 whichextends along the tubular element and bridges the two sets ofco-operating flanges.

The anchoring strap 74 is bolted or otherwise secured to the peripheryof the wheel rim. It will be noted that the anchoring means are notshown in FIG. 18 to permit illustration of the co-operating flangeportions.

Each flange 55, 57 is formed with raised rib 75 adjacent the free edgeon the face opposite to the mounting face 59. The raised ribs 75facilitate positive engagement between the anchoring strap 74 and theflanges.

The outwardly directed flange portions 65, 66 are also profiled at 76 toprovide a seat for the portion 77 of the tubular element which bridgesthe spaced flange sections 61, 63.

The mounting arrangement permits any segment to be replaced easily if itbecomes damaged.

The embodiment shown in FIGS. 21 to 24 of the drawings is directed to aground engaging surface in the form of a tire 81 for a wheel 83.

The tire 81 comprises a plurality of rows of hollow, ground engagingelements 85, there being three such rows shown in this embodiment. Eachelement 85 is provided by a loop of resilient material.

The loops in each row are formed by a length of elastomeric material 87arranged in sinuous formation having a plurality of crests and troughs.The length of the material is anchored to the peripheral rim of thewheel 83 by fixing means 89 at locations corresponding to each of thetroughs. The fixing means 89 are each in the form of a reinforcing plate90 anchored to the rim of the wheel by bolts.

The ground engaging elements of each row are offset with respect to theground engaging elements in neighbouring rows, as best seen in FIG. 21of the drawings. In this way, the tire has a peripheral surface whichcan roll in a more uniform manner than it would be capable of if thetread elements in each row were transversely aligned.

While the sinuous length of material may be located directly on theperipheral rim of the wheel, in this embodiment they are located on aninner band 91 which is fitted onto the rim of the wheel.

The ground engaging elements 85 provide the wheel with traction whenoperating on unstable ground. Because of their resilient nature, thetread elements can deform when the wheel is operating on finished roadsurfaces. This is beneficial in that it reduces the likelihood of damageto the finished road surface and provides a degree of springing which atleast partially absorbs shock forces resulting from bumps and othersurface irregularities encountered in the part of the wheel.

The embodiment shown in FIGS. 25 and 26 is directed to a ground engagingelement which can be applied to the existing tracks of vehicles whichare supported by endless tracks such as earth moving equipment andmilitary equipment. It is a function of the embodiment to provide ameans for converting the tracks of endless tracks vehicles for suchvehicles to be able to run on roads without causing damage to the road.It is believed that such conversion will enable the vehicle to be usedin off-road circumstance with a reduced possibility of bogging than withpresent conversion systems. According to current techniques ofconverting endless tracks to a form suitable for running on roads, theaggression provided by the track is greatly eliminated and in order fora vehicle to be able to be used again in off road conditions it isnecessary that the tracks be reconverted.

The present embodiment comprises utilization of ground engaging elementswhich are of a tubular configuration and partly circular cross-section.The elements 101 are formed with an arcuate portion 102 interconnectedby a substantially flat web portion 103. The interior face of the flatweb portion is associated with a reinforcing strip 104 which extendssubstantially with full width of the web 103. A number of holes (notshown) are provided in the length of the flat web 103 and thereinforcing plate 104 to facilitate fixing to an endless track. As shownin the drawings, the ground engaging elements 101 are applied in side byside parallel relationship transversely across an endless track 105whereby the arcuate portion 102 provides the support surface for thetrack.

In the case of vehicles formed with a grouser plate 106, the groundengaging elements 101 are fixed between the upstanding ribs 105 of thegrouser plates. In this case of earth moving equipment which utilisechain elements 108 the elements are mounted to the chains of the endlesstrack of the vehicle.

As a result of the embodiment a resilient ground engaging surface isprovided which avoids the damage to a road surface that would beotherwise caused by the use of unprotected conventional endless tracksutilized with military and earth moving vehicles. In addition in theevent that the converted vehicle is required for immediate off road usethe converted track has inherent aggression which facilitates suchutilization with a reduced possibility of bogging. In the case ofmilitary vehicles there is no time lost in converting a vehicle for usefrom off road to on road use or vice versa.

As shown in FIG. 17 where the tubular elements 51 are sufficientlyclosely spaced for the side walls of one element 51 to engage those ofits adjacent neighbors when the elements 51 deform resiliently underload, and in FIG. 26 where the tubular elements 101 are mounted withtheir side walls abutting, the tubular elements of this invention, withtheir resiliently deformable side walls, are able to provide mutuallateral support under load.

It should be appreciated that the scope of the invention is not limitedto the scope of the embodiment described. It should in particular beunderstood embodiments described can be applied to either wheels orendless tracks even though they may have been described in relation toonly one application.

I claim:
 1. A durable, closed-loop, mobile, multiple-element supportsystem providing cushioning support on an engaged ground surface, saidsupport system comprising:a) a closed loop member mountable for cyclicalmovement about a support structure, said closed loop member having asupport face; and b) a plurality of ground-engaging load-bearingelements secured on said support face, each of said ground-engagingelements comprising:i) an inner element portion bearing on said supportface to transmit ground-engaging loads to said support face; ii) anouter element portion with a discrete outer surface for engaging theground, said outer element portion being positioned in an outwarddirection away from said inner element portion and in facing spacedrelationship to said inner element portion said outer portion having athickness in the radial direction with respect to said closed loopmember; iii) load-bearing deformable side walls in facing spacedrelationship to each other and extending from said outer element portiontoward said support face, said deformable side walls having a side wallthickness, a height in the radial direction and a width, said sidewallthickness being smaller than the thickness of said outer elementportion, said sidewalls deforming under load to support said closed loopmember with said outer element in engagement with said engaged groundsurface; and iv) a ventilation cavity defined between said side walls,and between said inner element portion and said outer element portionsaid ventilation cavity having a cavity height in said radial direction,said height being greater than said thickness of said outer portion andhaving a clear heat-dissipating volume opening to the ambient at a firstorifice, said deformable side walls being constructed to reduce saidcavity height in response to the application of a normal ground-engagingload on said outer element and resiliently to absorb said normal loadwhile maintaining a clear heat-dissipating volume in said ventilationcavity.
 2. A support system as in claim 1, wherein said discrete outersurface is parallel to said support face and wherein said inner elementportion is shaped to fit said support face, wherein both of said sidewalls are integrally connected to said inner element portion and whereinsaid side walls meet said inner element portion at said support facewith squared corners.
 3. A support system as in claim 1, wherein saidside walls have inner side-wall surfaces within said ventilation cavity,said inner side wall surfaces being configured with an angular bend atan intermediate portion of said inner side-wall surfaces between saidinner and outer element portions, said angular bend promotingdeformation of said side walls in directions laterally outward of saidventilation cavity.
 4. A support system as in claim 1, wherein saidventilation cavity extends transversely between said first orifice and asecond orifice, said first and second orifices opening to opposite sidesof said support system, and wherein said ground-engaging element has anelement height in said outward direction and said cavity height is atleast half as great as said element height and said orifices have anorifice height no less than said cavity height.
 5. A support system asin claim 1, wherein said side walls of each element extendperpendicularly to said support face in said outward direction anddiverge from each other in said outward direction to a zone of maximumgirth of said element, said zone of maximum girth having a greaterextent than said discrete outer surface and said load-bearing elementsare positioned adjacent to each other on said closed loop member.
 6. Asupport system according to claim 1 further comprising a mounting meansfor detachably mounting each said element on said support surface, saiddetachable mounting means extending from said ventilation cavity throughsaid inner element portion and being cooperative with said closed loopmember for secural of said element to said closed loop member, saidmounting means and said element being cooperative to provide said clearheat-dissipating volume in said ventilation cavity under load.
 7. Acomposite, non-pneumatic tire for a wheel, said tire comprising aclosed-loop, multiple-element support system according to claim
 1. 8. Asupport system as in claim 1 wherein each said element has a chevronshape in a plane perpendicular to said outward direction and saidchevron-shaped elements interfit one with another around said closedloop member.
 9. A hollow, resilient, ground-engaging, load-bearingelement for a closed-loop, mobile, multiple-element, support systemcomprising a closed-loop member mountable for cyclical movement about anaxis extending through a support structure, said closed-loop memberhaving a peripheral support surface for receiving a plurality of saidground-engaging load-bearing elements, one or a number of which elementsdurably support the mobile apparatus in a ground-engaging position, withcushioning, said ground-engaging element comprising:a) an inner elementportion securable to said closed-loop member to bear on said supportsurface to transmit ground-engaging loads to said support surface; b) anouter element portion with a discrete outer surface for engaging theground, said outer element portion being positioned in an outwarddirection radially outward of said support structure, away from saidinner element portion in spaced relationship to said inner elementportion said outer portion having a thickness in the radial directionwith respect to said closed loop member; c) load-bearing side wallsconfigured to be deformed, positioned in facing spaced relationship toeach other and extending between said inner and outer element portions,said side walls being deformable to permit movement of said outerelement portion towards said inner element portion in response to loadssaid deformable side walls having a side wall thickness, a height in theradial direction and a width, said sidewall thickness being smaller thanthe thickness of said outer element portion, said sidewalls deformingunder load to support said closed loop member with said outer elementportion in engagement with said support surface; and d) a ventilationcavity defined between said inner and outer element portions and saidside walls, said cavity having an opening, said opening being positionedto put said cavity in pneumatic communication with ambient air adjacentsaid ground-engaging element for ventilating said element, said cavityhaving a cavity height in said radial direction, said cavity heightbeing greater than said thickness of said outer portion and providing aclear heat-dissipating volume within said cavity;said discrete outersurfaces of said plurality of ground-engaging elements extending alongand defining an outer ground-contacting periphery of said support systemwhen said plurality of elements is secured to said support surface,wherein deformation of said side walls in response to said normal,straight-line, direction-of-travel loads reduces said cavity heightwhile maintaining a clear heat-dissipating volume within said cavitywhereby a plurality of said elements received on to said support systemabsorb ground-engaging loads in said outward direction in a resilient,cushioning manner.
 10. An element according to claim 9, wherein saidside walls are configured to deform outwardly of the ventilation cavityin response to a ground-engaging load directed perpendicularly from saidouter surface towards said support member, said side walls supportingsaid outer element portion with the provision of a clearheat-dissipating ventilation cavity while deformed.
 11. An elementaccording to claim 10, wherein each said deformable side wall has aportion intermediate said cavity height and movable outwardly of saidventilation cavity under load.
 12. An element according to claim 11,wherein said side walls each have an angular profile between said innerand outer element portions said side wall profile comprising two innerlongitudinal surfaces, said longitudinal surfaces meeting at a line atwhich each said side wall can deform.
 13. An element according to claim9, wherein said side walls have outer surfaces diverging outwardly fromsaid inner surface of said inner portion of said ground-engaging elementto a zone of maximum girth of said element and wherein, said element hasan inner structure including said inner portion and including saiddivergent outer side wall surfaces and has an outer structure includingsaid outer element portion, said outer structure being operative totransmit said ground-engaging loads to urge said side wall surfacesapart.
 14. An element according to claim 9, wherein each side wall hasat least two mutually angled faces, said element being securable to saidclosed loop member with each said angled face inclined to the directionof travel.
 15. An element according to claim 14, said element beingv-shaped to have a chevron-like appearance, in a plane perpendicular tosaid outward direction.
 16. An element according to claim 9, whereinsaid outer element portion comprises tread means said tread meansproviding said discrete outer surface and extending parallel to saidperipheral support surface and inclined to said direction of movement ofsaid support structure, when secured on said closed loop member.
 17. Anelement according to claim 9, wherein said discrete outerground-engaging surface is arcuate and presents an outwardly facingconvex surface curved to be parallel to said support surface when saidelement is secured to said closed loop member.
 18. An element accordingto claim 9, wherein said inner element portion has an inner surfaceshaped to lie snugly against said support surface, said side walls joinsaid inner element portion with squared corners and said element has ablock-like shape in section, viewed in the direction of said axis ofsaid cyclical movement, said block-like shape being defined by outerperipheries of said inner and outer element portions and said side wallsand providing structural integrity resisting twisting ground-engagingforces on said element about an axis perpendicular to said section andtransmitting said rotational forces to said element support surface. 19.An element according to claim 9, wherein said ventilation cavity has acavity width between said side walls which is greater than the sum ofthe side wall thicknesses.
 20. An element according to claim 9, havingopenings in said inner portion to receive mounting means to hold saidelement on said support surface.
 21. An element according to claim 20,in combination with mounting means for detachably mounting said elementon said support surface, said detachable mounting means extending fromsaid ventilation cavity through said openings in said inner elementportion and being cooperative with said closed loop member for securalto said closed loop member, said detachable mounting means beingcontainable within said cavity save for structure extending through saidopenings in said inner element portion.
 22. In combination, a vehiclewheel rim, a composite non-pneumatic tire secured to said wheel rim andclamping member and securing means, said composite non-pneumatic tirecomprising multiple tire segments each said tire segment being tubularand being clampable against said rim by a clamp member locatableinternally of said segment, multiple said tire segments being mountablearound said wheel rim to lie across said wheel rim in side-by-siderelationship and to open to ambient on either side of said rim, therebyproviding said composite tire, said tire segment comprising:a) an outerground-engaging portion bearing a ground-engaging surface delimited bycorners said outer portion having a thickness in the radial directionwith respect to said closed loop member; b) an inner load-bearingportion to bear on said wheel rim to transmit loads to said wheel rim,said inner portion being radially apertured to receive said tire segmentsecuring means c) a tubular ventilation cavity between said outerground-engaging portion and said inner load-bearing portion, said cavityopening to ambient on either side of said rim and having a cavity heightgreater than said thickness of said outer portion; d) deformable sidewalls extending between said inner load bearing portion and said outerground-engaging portion and embracing said ventilation cavity saiddeformable side walls having a side wall thickness, a height in theradial direction and a width, said sidewall thickness being smaller thanthe thickness of said outer element portion, said sidewalls deformingunder load to support said closed loop member with said outer element inengagement with said support surface; e) aperturing in said innerload-bearing portion opening into said ventilation cavity, said clampmember securing means having an extension projecting through saidaperturing, whereby said securing means can extend from said ventilationcavity and through said aperturing to cooperate with said adapted rimand secure said clamping member to hold said tire segment against saidrim;wherein said ventilation cavity is dimensioned to receive saidclamping member and said extension for mounting said segments aroundsaid rim, and wherein said side walls deform under load permitting saidouter ground-engaging portion to move toward said inner load-bearingportion, said clamping members and securing means being locatedinternally of said tire segments, with said extensions extending throughsaid inner load-bearing portions of said tire segments and engaging withsaid wheel rim.